The UK government’s climate change adviser has launched a scathing attack on Australia’s net zero commitment on the eve of critical talks in Glasgow.Lord Deben, the Climate Change Committee chair, told the BBC on Saturday there was “no indication” that the Australian prime minister, Scott Morrison, had a plan to deliver on the commitment to net zero that was “squeezed out of him”.“It’s very sad that a great country like Australia should change our climate,” he said.“Because that’s what happens. If you allow people to keep on doing this, it’s our climate as well as theirs that’s changed.”Morrison is in Rome for the G20 summit, and on his way to Glasgow for Cop26, after initially appearing reluctant to make the trip.He says the federal government has a plan to meet the net zero target, but has announced no new policies, no real details, and is relying on future technology “breakthroughs” to meet the target.Experts say the claim carbon offsets could reduce emissions by up to 20% relies on a “gross manipulation” of data.Morrison’s “projection” of a 30-35% emissions reduction by 2030 is not a new target – Morrison is sticking with the current target to reduce emissions by up to 28% on 2005 levels.Lord Deben says he would ‘love to see Australia rejoin the pack’ and most leaders are beginning to recognise how serious the threat of climate change is. Photograph: Troika/AlamyLord Deben, who was a minister in Margaret Thatcher’s conservative government and environment minister under her successor John Major, said most world leaders were beginning to recognise how serious the threat of climate change is.“(But) not all leaders are like that. I’m afraid that if you look at Scott Morrison from Australia, we’ve squeezed out of him a commitment to net zero in 2050 but there’s no indication at the moment that he’s got a proper program for that,” he said.“But in general the world has changed.”Lord Deben said he would “love to see Australia rejoin the pack”, and that climate change was an existential threat.“If we don’t do it then we really do risk the destruction of everything we’ve ever known,” he said.Sign up to receive the top stories from Guardian Australia every morningIt’s not the first time Lord Deben has singled Australia out for criticism. In September he said Australia was “recalcitrant”. He also warned Australia would be “left behind”, and should really understand what needs to be done.Back in 2015 he said the then prime minister Tony Abbott’s 2030 target – which remains under Morrison – was “pathetic”.“Global warming won’t wait for Mr Abbott and his government. Mr Abbott’s hubris is staggering,” he said.From Rome, Morrison said Australia’s policy was a “significant commitment” and compared it to the hunt for a Covid vaccine.Quick GuideHow to get the latest news from Guardian AustraliaShowPhotograph: Tim Robberts/Stone RFThank you for your feedback.“(I’m) looking forward to updating other leaders on our plans and programs, particularly on our keenness to work with other countries on those technology breakthroughs that frankly, when you’re talking about hitting net zero emissions, it’s the same sort of challenge the world faced when you’re looking for a vaccine, a vaccine to end the pandemic,” he said.Asked if he thought Glasgow might “end up a bit of a damp squib” because China and others were not turning up, he said: “Australia’s taking steps forward. We’re taking strong steps forward.”Morrison also said he would meet with Australia’s former finance minister Mathias Cormann. In his new job as the Organisation for Economic Co-operation and Development secretary general, Cormann has called for a price on carbon despite sinking a carbon price plan when he was in government.